Air induction systems for internal combustion engines typically employ a substantially tubular air duct within which to transport clean air from a filter to at least the inlet manifold, or throttle body, of the engine. Similarly, tubular air ducts are used to convey air from the engine compartment into a heating and ventilating system in the passenger compartment. One or more of these air ducts often require additional ports on the tubular body to allow air to be directed to and from other devices on the vehicle. For example, an exhaust gas recirculation system is provided in most vehicles to reduce the exhaust emissions of the engine.
In order conveniently to accommodate any passages which are to branch laterally outwardly from the air duct, a port must be attached to the air duct. Such port attachments are frequently accomplished by heat welding or adhesives. While this method of securing a laterally disposed port to the air duct may result in a satisfactory porting arrangement, it is time consuming and adds significant expense to the overall cost of the air duct. The aforesaid prior art method also requires sufficient testing after the side port is installed to ensure that no air leakage between the port and the main body of the air vent will occur during operation of the vehicle. Air leakage during vehicle operation can result in excess emissions or reduced efficiency of the engine and, therefore, reduced fuel mileage. Such leakage could also permit the entrainment of solid particles in the air stream that might well result in stalling of, or damage to, the engine.
Porting arrangements have heretofore been incorporated in blow molded articles such as fuel tanks and cylindrical containers by several known variations of the blow molding technique. With reference to U.S. Pat. No. 5,104,472 it will be observed that after the piece is removed from the mold the desired holes must be punched.
By way of another example, fuel tanks, such as that described in U.S. Pat. No. 4,877,147, may incorporate a vent tube that is positioned in the mold cavity to be secured to, or embedded within, the tank wall during the blow molding process. The securement of the vent tube to, or in, the container wall is accomplished by causing the parison to flow against, and/or around, a flanged vent tube. It should be noted that the free end of the conduit is bevelled. The resulting pointed end of the vent tube more easily pierces the parison wall. Also, the beveled end is less likely to remove a plug of material from the parison wall which might clog the vent tube.
In blow molded cylindrical containers, such as that shown in U.S. Pat. No. 3,919,374, a plug may be secured into an opening of the container during the molding process. This requires that the parison be extruded circumferentially around and past the plug. When the mold is closed, the remote, open end of the parison is pinched closed by the opposed mold halves. The plug is then captured in its own receiving cavity located along the split line of the mold so that as the mold is closed, the parison is forced into the space surrounding the plug, such that the plug is mechanically secured to the open end of the blow molded container.